Retransmission apparatus, system and method for retransmitting broadcast packets

ABSTRACT

A retransmission apparatus retransmits TS (Transport Stream) packets based on a received broadcast wave to a plurality of receiving apparatus through a network. The retransmission apparatus has a TS packet determination unit for determining whether a continuity of circulation counter values in the TS packets keeps in length equal to or more larger than a first predetermined threshold value N, and for retransmitting these TS packets when the determination is true, or for canceling these TS packets when the determination is false. Also, the TS packet determination unit determines whether a discontinuity of circulation counter values in the TS packets keeps in length equal to or more larger than a second predetermined threshold value T without retransmitting these TS packets, and sends an “off service” signal to a plurality of receiving apparatus when the determination is true.

PRIORITY CLAIM

The present application claims priority from Japanese Patent ApplicationNo. 2007-256919 filed on Sep. 29, 2007, which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a retransmission apparatus, a systemand a method for retransmitting broadcast packets.

2. Description of the Related Art

Recently, there is a service that TS (Transport Stream) packets of theterrestrial digital broadcasting or MPEG2-TS packets are transmittedthrough IP (Internet Protocol) network by multicast communication. Forexample, there is a document by KDDI Corporation, “On action of thetelecommunications service broadcasting business and IP retransmissionof the terrestrial digital broadcast by KDDI”,(http://www.soumu.go.jp/joho_tsusin/policyreports/joho_tsusin/joho_bukai/pdf/051118_(—)1_(—)04.pdf),Nov. 18, 2005. Specifically, digital broadcast wave is received by usingan antenna, and TS packets in the receive signal are retransmitted to aplurality of receiving apparatus through an IP network.

FIG. 1 is a system configuration diagram in a related art.

According to FIG. 1, a digital broadcast wave (RF (Radio Frequency)signal) broadcasted from a broadcasting station 4 is received by anantenna 12. The antenna 12 is connected to tuners 11. A tuner 11 tunesup to a specific channel of broadcast waves. The tuner 11 gets TSpackets from the broadcast wave tuned up, and the TS packet is sent to aretransmission apparatus 10.

The retransmission apparatus 10 generates an IP packet whose payload isTS packets outputted from the tuner 11. The IP packet is sent to aplurality of receiving apparatus 2 through an IP network 3.

The receiving apparatus 2 pulls out TS packets from the IP packetreceived through the IP network 3. Then, the TS packets are convertedinto an RF signal. The RF signal is output to playback apparatus 5 suchas television sets.

The sequence in FIG. 1 shows the case that digital broadcast wavebroadcasted from the broadcasting station 4 is not received by antenna12. For example, the digital broadcast wave received through air isstopped at times or cannot be received depending on a time or a place.In such cases, no RF signal is input into the tuner 11 connected to theantenna 12. Then, the tuner 11 may be designed to output invalid TSpackets continuously to stabilize the output rate of TS packets. At thistime, retransmission apparatus 10 sends all these invalid TS packets tothe receiving apparatus 2 through IP network 3.

According to the above-mentioned art, however, the invalid TS packetsadded by the tuner are not substantially necessary. During the state ofbroadcasting stop, only in order to stabilize the output rate of TSpackets to the receiving apparatus 2, invalid data are sent to IPnetwork 3 continuously. This means that limited communication resourceis wasted.

Further, when receiving the invalid TS packets added by the tuner, thereceiving apparatus 2 determines that it is the state of broadcast stop.On the other hand, when receiving no TS packet at all, the receivingapparatus 2 determines that IP network 3 itself is a failure.

BRIEF SUMMARY OF THE INVENTION

The object of the present invention is to provide a retransmissionapparatus, a system and a method for retransmitting the broadcastpackets, which is explicitly able to inform a plurality of receivingapparatus of that broadcast wave itself cannot be received, withoutwasting communication resources in an IP network.

According to the present invention, the retransmission apparatus forretransmitting TS packets based on received broadcast wave to aplurality of receiving apparatus through a network, has

TS packet determination unit for determining whether a continuity ofcirculation counter values in the TS packets keeps equal to or morelarger than a first predetermined threshold value N, and forretransmitting these TS packets when the determination is true, or forcanceling these TS packets when the determination is false.

It is preferred that the TS packet determination unit determines whethera discontinuity of circulation counter values in the TS packets keepsequal to or more larger than a second predetermined threshold value Twithout retransmitting these TS packets, and sends an off service signalto a plurality of receiving apparatus when the determination is true.

It is preferred that for the case that the circulation counter value ofthe current TS packet is continuous to the circulation counter value ofthe adjacent TS packet,

the TS packet determination unit reserves the current TS packet, setsthe continuous number of normally received packets n=n+1, sets thediscontinuous number for cancellation t=t+1, and transmits all TSpackets reserved in the buffer, then sets t=0, when the continuousnumber of normally received packets n is determined to be equal to orlarger than the first predetermined value N.

It is preferred that for the case that the circulation counter value ofcurrent TS packet is discontinuous to the circulation counter value ofthe adjacent TS packet,

the TS packet determination unit cancels all TS packets reserved,reserves current TS packet into a buffer, sets the continuous number ofnormally received packets n=0, sets the discontinuous number forcancellation t=t+1, and sends off service signal, when the discontinuousnumber for cancellation t is determined to be equal to a secondpredetermined value T.

It is preferred that TS packet is based on the standard of ARIB STD-B31,and a circulation counter value is a value of TSP_counter.

It is preferred that the apparatus further has

payload formation unit for forming a payload out of TS packets from theTS packet determination unit,

RTP processing unit for generating an RTP packet from the payload,

IP multicast sending means for forming RTP packet into IP packet sent toa plurality of receiving apparatus by multicast communication.

It is preferred that the retransmission system has

antenna for receiving digital broadcast wave signal from a broadcastingstation,

a plurality of tuners connected to the antenna for tuning every channel,and

a plurality of retransmission apparatus claimed in claim 1 connected tothe tuner, wherein

the retransmission system sends IP packets including TS packets to aplurality of receiving apparatus through an IP network.

It is preferred that the retransmission method on the apparatus thatreceives TS packets based on a broadcast wave, for retransmitting TSpackets to a plurality of receiving apparatus through a network, whereinthe method has the steps of:

taking a circulation counter value in a TS packet at every TS packetinput,

determining whether a continuity of circulation counter values keepsequal to or larger than a first predetermined threshold value N, and

retransmitting these TS packet when the determination is true, orcanceling these TS packets when the determination is false.

It is preferred that the retransmission method for making a computer tofunction as a retransmission apparatus for retransmitting TS packetsbased on received broadcast wave to a plurality of receiving apparatusthrough a network, wherein the retransmission method has the steps of:

taking a circulation counter value in a TS packet at every TS packetinputting,

determining whether a continuity of circulation counter values keepsequal to or larger than a first predetermined threshold value N, andretransmitting these TS packet when the determination is true, orcanceling these TS packets when the determination is false.

According to the retransmission apparatus, the system and the method ofthe present invention for retransmitting the broadcast packets, which isexplicitly able to inform a plurality of receiving apparatus of thatbroadcast wave itself cannot be received, without wasting communicationresources in an IP network.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a system configuration diagram in a related art.

FIG. 2 is a system configuration diagram in the present invention.

FIG. 3 is a functional configuration diagram of a retransmissionapparatus in the present invention.

FIG. 4 is a frame configuration diagram of a TS packet.

FIG. 5 is an illustration of TS packet retransmission state in theretransmission apparatus of the present invention.

FIG. 6 is a flow chart of TS packet determination unit in theretransmission apparatus of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2 is a system configuration diagram in the present invention.

According to FIG. 2, compared with FIG. 1, a retransmission unit 10generates IP packets based on only TS packets whose circulation countervalues keep continuity equal to or more larger than a predeterminedthreshold value N. The circulation counter value of a TS packetincrements continuously as far as TS packets are received normally. TheIP packet is sent to a plurality of receiving apparatus 2. Thereby, itis not necessary to send invalid TS packets to an IP network 3.

In the case that the TS packet is based on an ARIB STD-B31 standard, acirculation counter value is a TSP counter value (TSP_counter). Theretransmission unit 10 always confirms the continuity of the TSP countervalue in a TS packet received from the tuner 11. Thus, when thecontinuity is confirmed, continuous TS packets are assumed to be valid,and are formed into an IP packet. The IP packet is sent to the receivingapparatus 2 through the IP network 3.

On the other hand, the discontinuous TS packet is canceled. Also, if thediscontinuity of circulation counter values in the TS packets keeps inlength equal to or more larger than a second predetermined thresholdvalue T without retransmitting these TS packets, “off service” signal issent to receiving apparatus 2. Thereby, receiving apparatus 2 recognizethat broadcast wave is stopped. The retransmission unit 10 notifiesexplicitly receiving apparatus 2 that it is not a failure in the IPnetwork 3.

FIG. 3 is a functional configuration diagram of the retransmissionapparatus in the present invention.

According to FIG. 3, a retransmission system 1 retransmits digitalbroadcast wave received from a broadcasting station 4, to a plurality ofreceiving apparatus 2 connected to the IP network 3. Such retransmissionsystem 1 is provided by a carrier or a broadcast enterprise. Theretransmission system 1 has a combination of retransmission apparatus 10and tuner 11 for every channel. Also, the retransmission apparatus 10transmits IP packets to plural receiving apparatus 2 by multicastcommunication through the IP network 3. A user of playback apparatus 5connected to a receiving apparatus 2 sees and hears a channel selectedby a tuner 11 and retransmitted by the retransmission system 1.

According to FIG. 3, a retransmission apparatus 10 has a TS packetreceiving unit 101, a TS packet determination unit 102, a payloadformation unit 103, a RTP (Real-time Transport Protocol) processing unit104 and an IP multicast sending unit 105. These functional configurationunits can be realized by executing programs to make functions by acomputer carried by the retransmission apparatus 10.

The TS packet receiving unit 101 receives TS packets in a specificchannel from the tuner 11. The received TS packets are output to the TSpacket determination unit 102.

The TS packet determination unit 102 determines whether a continuity ofcirculation counter values in the TS packets keeps in length equal to ormore larger than the first predetermined threshold value N. These TSpackets are retransmitted when the determination is true, or arecanceled when the determination is false. Also, the TS packetdetermination unit 102 further determines whether a discontinuity ofcirculation counter values in the TS packets keeps in length equal to ormore larger than a second predetermined threshold value T withoutretransmitting these TS packets. When the determination is true, “offservice” signal is sent to receiving apparatus 2. The TS packetdetermination unit 102 is a special feature part in the presentinvention.

The payload formation unit 103 forms a payload out of TS packets fromthe TS packet determination unit 102. The formed payload is output tothe RTP processing unit 104.

The RTP processing unit 104 generates a RTP packet from the payload. Thegenerated RTP packet is output to the IP multicast sending unit 105.

The IP multicast sending unit 105 forms an RTP packet into an IP packet.The IP packet is sent to a plurality of receiving apparatus 2 bymulticast communication.

On the other hand, the receiving apparatus 2 has an IP packet receivingunit 21, a RTP processing unit 22 and a RF signal generator 23. The IPpacket receiving unit 21 receives IP packets from the retransmissionapparatus 10 through the IP network 3, and removes IP header from the IPpacket to form an RTP packet output to the RTP processing unit 22. TheRTP processing unit 22 removes an RTP header from the RTP packet to forma TS packet. The TS packet is output to the RF signal generator 23. TheRF signal generator 23 generates RF signal from the TS packet. The RFsignal is output to playback equipments 5.

FIG. 4 is a frame configuration diagram of the TS packet.

According to FIG. 4, there continues a plurality of TS packets based onthe ARIB STD-B31 standard. The TS packet has a synchronizing flag,information part and a dummy bytes part. The dummy bytes part hastransmission control information and optional parity bytes. Acirculation counter value is a value of “TSP_counter” in“ISDB-T_information( )”. The maximum value of TSP_counter variesdepending on a modulation mode of the digital broadcasting. Therefore,the retransmission apparatus 10 gets a modulation parameter from a TSpacket in advance to recognize the appropriate maximum value.

FIG. 5 is an illustration of the TS packet retransmission state in theretransmission apparatus of the present invention.

According to FIG. 5, both a vertical axis and a horizontal axis showelapsed time. The horizontal axis shows receiving order of TS packetsand TSP counter values. The vertical axis shows time points when the TSpackets are determined to be “valid (shown with o)” or” “invalid (shownwith X)”.

The following values are also used:

n: the continuous numbers of normally received packets that TSP countervalues are continuous,

N: the threshold value of n for determining to be “valid” (for example,N=4),

t: the discontinuous number for cancellation,

T: threshold value of t for determining to be “invalid” and for sendingan off service signal (for example, T=5),

NS: the TSP counter value of a current received TS packet,

BS: the TSP counter value of the adjacent received TS packet.

The discontinuous number for cancellation t is specifically shown asfollows:

the discontinuous number for cancellation t=(the number of receivedpackets that have been canceled)+(the number of received packets thatare possible to be canceled in the future)

“The number of received packets that are possible to be canceled in thefuture” does not depend on the continuity/discontinuity of the TSPcounter values. That is to say, even if TSP counter values arecontinuous, the discontinuous number for cancellation t is set to t+1(t=t+1). Because, even if TSP counter values are continuous, these TSpackets are possible to be canceled unless the continuous number ofnormally received packets n becomes equal to or more larger than thethreshold value N.

First, the TSP counter value of the adjacent received TS packet BS isset to −1 (BS=−1).

-   (S501) When the current TSP counter value [99] is received, it is    discontinuous to the adjacent TSP counter value [−1]. Therefore, the    TS packet [99] is reserved, and the discontinuous number for    cancellation t is set to 1 (t=1) (the continuous number of normally    received packets n=0).-   (S502) When the current TSP counter value [52] is received, it is    discontinuous to the adjacent TSP counter value [99]. Therefore, the    TS packet [99] is canceled, and the TS packet [52] is reserved.    Further, the discontinuous number for cancellation t is set to 2    (t=2) (the continuous number of normally received packets n=0).-   (S503) When the current TSP counter value [16] is received, it is    discontinuous to the adjacent TSP counter value [52]. Therefore, the    TS packet [52] is canceled, and the TS packet [16] is reserved.    Further, the discontinuous number for cancellation t is set to 3    (t=3) (the continuous number of normally received packets n=0).-   (S504) When the current TSP counter value [17] is received, it is    continuous to the adjacent TSP counter value [16]. Therefore, the TS    packet [17] is further reserved, and the continuous number of    normally received packets n is set to 1 (n=1) (the discontinuous    number for cancellation t=4).-   (S505) When the current TSP counter value [18] is received, it is    continuous to the adjacent TSP counter value [17]. Therefore, the TS    packet [18] is reserved, and the continuous number of normally    received packets n is set to 2 (n=2) (the discontinuous number for    cancellation t=5).-   (S506) When the current TSP counter value [19] is received, it is    continuous to the adjacent TSP counter value [18]. Therefore, the TS    packet [19] is reserved, and the continuous number of normally    received packets n is set to 3 (n=3) (the discontinuous number for    cancellation t=6).-   (S507) When the current TSP counter value [20] is received, it is    continuous to the adjacent TSP counter value [19]. Therefore, the TS    packet [20] is reserved, and the continuous number of normally    received packets n is set to 4 (n=4). Then, for n=N=4, all reserved    TS packets [16], [17], [18], [19] and [20] are determined to be    valid, and are transmitted to the receiving apparatus 2. And, the    discontinuous number for cancellation t is reset to zero (t=0).-   (S508) When the current TSP counter value [21] is received, it is    continuous to the adjacent TSP counter value [20]. Therefore, TS    packet [21] is determined to be valid, and is transmitted to    receiving apparatus 2. And the continuous number of normally    received packets is set to 5 (n=5) (the discontinuous number for    cancellation t=0).-   (S509) When the current TSP counter value [22] is received, it is    continuous to the adjacent TSP counter value [21]. Therefore, TS    packet [22] is determined to be valid, and is transmitted to    receiving apparatus 2. And the continuous number of normally    received packets is set to 6 (n=6) (the discontinuous number for    cancellation t=0).-   (S510) When the current TSP counter value [25] is received, it is    discontinuous to the adjacent TSP counter value [22]. Therefore, the    TS packet [25] is reserved, the discontinuous number for    cancellation t is set to 1 (t=1), and the continuous number of    normally received packets n is set to zero (n=0).-   (S511) When the current TSP counter value [31] is received, it is    discontinuous to the adjacent TSP counter value [25]. Therefore, the    TS packet [25] is canceled, and the TS packet [31] is reserved.    Further, the discontinuous number for cancellation t is set to 2    (t=2) (the continuous number of normally received packets n=0).-   (S512) When the current TSP counter value [32] is received, it is    continuous to the adjacent TSP counter value [31]. Therefore, the TS    packet [32] is reserved, and the continuous number of normally    received packets n is set to 1 (n=1) (the discontinuous number for    cancellation t=3).-   (S513) When the current TSP counter value [33] is received, it is    continuous to the adjacent TSP counter value [32]. Therefore, the TS    packet [33] is reserved, and the continuous number of normally    received packets n is set to 2 (n=2) (the discontinuous number for    cancellation t=4).-   (S514) When the current TSP counter value [68] is received, it is    discontinuous to the adjacent TSP counter value [33]. Therefore, the    TS packets [31], [32] and [33] are canceled, and the TS packet [68]    is reserved. Further, the discontinuous number for cancellation t is    set to 5 (t=5), and the continuous number of normally received    packets is reset to 0 (n=0). Then, for t=T=5, “off service” signal    is sent to receiving apparatus 2.-   (S515) When the current TSP counter value [86] is received, it is    discontinuous to the adjacent TSP counter value [68]. Therefore, the    TS packet [68] is canceled, and the TS packet [86] is reserved.    Further, the discontinuous number for cancellation t is set to 6    (t=6), (the continuous number of normally received packets n=0).-   (S516) When the current TSP counter value [87] is received, it is    continuous to the adjacent TSP counter value [86]. Therefore, the TS    packet [87] is reserved, and the continuous number of normally    received packets n is set to 1 (n=1) (the discontinuous number for    cancellation t=7).-   (S517) When the current TSP counter value [88] is received, it is    continuous to the adjacent TSP counter value [87]. Therefore, the TS    packet [88] is reserved, and the continuous number of normally    received packets n is set to 2 (n=2) (the discontinuous number for    cancellation t=8).-   (S518) When the current TSP counter value [89] is received, it is    continuous to the adjacent TSP counter value [88]. Therefore, the TS    packet [89] is reserved, and the continuous number of normally    received packets n is set to 3 (n=3) (the discontinuous number for    cancellation t=9).-   (S519) When the current TSP counter value [90] is received, it is    continuous to the adjacent TSP counter value [89]. Therefore, the TS    packet [90] is reserved, and the continuous number of normally    received packets n is set to 4 (n=4). Then, for n=N=4, all reserved    TS packets [86], [87], [88], [89] and [90] are determined to be    valid, and are transmitted to the receiving apparatus 2. And, the    discontinuous number for cancellation t is reset to zero (t=0).-   (S520) When the current TSP counter value [91] is received, it is    continuous to the adjacent TSP counter value [90]. Then, TS packet    [91] is determined to be valid, and is transmitted to the receiving    apparatus 2. Further, the continuous number of normally received    packets n is set to 5 (n=5) (the discontinuous number for    cancellation of received packets t=0).

FIG. 6 is a flow chart of the TS packet determination unit in theretransmission apparatus of the present invention.

The flow of FIG. 6 is executed by the TS packet determination unit 102after receiving a TS packet from the TS packet receiving unit 101.

-   (S601) First of all, TSP counter value (TSP_counter) is got from a    TS packet.-   (S602) It determines whether the current TSP counter value of the TS    packet is continuous to the already stored adjacent TSP counter    value.-   (S603) When the current TSP counter value is continuous to the    adjacent TSP counter value, the current TSP counter value is    substituted for the adjacent TSP counter value.-   (S604) The current received TS packet is reserved in a buffer. If    the continuous number of normally received packets n is smaller than    the threshold value N (n<N), a plurality of TS packets are reserved    in the buffer.-   (S605) The continuous number of normally received packets n is set    to n+1 (n=n+1).-   (S606) The discontinuous number for cancellation t is set to t=t+1.    Even if TSP counter values continue, if the continuous number of    normally received packets n does not become larger than the    threshold value N, these TS packets are possible to be canceled.-   (S607) It determines whether the continuous number of normally    received packets n is equal to or larger than the number of the    first predetermined threshold value N. If the continuous number of    normally received packets n is smaller than the threshold value N    (n<N), the reserved TS packets cannot be yet determined to be valid.    Thus, the process is just finished.-   (S608) If the continuous number of normally received packets n is    equal to or larger than the threshold value N (n≧N), all reserved TS    packets are determined to be continuous and valid. And, all reserved    TS packets are output to the payload formation unit 103, and is    transmitted to receiving apparatus 2.-   (S609) The discontinuous number for cancellation t is reset to zero    (t=0).-   (S613) If the current TSP counter value is not continuous to the    adjacent TSP counter value, all the reserved TS packets are    canceled.-   (S614) Then, the current TSP counter value is substituted for the    adjacent TSP counter value.-   (S615) The current received TS packet is reserved in the buffer. The    reason is that following the TS packet, normally continuous TS    packets may be received continuously.-   (S616) The continuous number of normally received packets n is reset    to zero (n=0).-   (S617) The discontinuous number for cancellation t is set to t+1    (t=t+1).-   (S618) It determines whether the discontinuous number for    cancellation t is equal to the threshold value T. If the    discontinuous number for cancellation t is not equal to the    threshold value T, the process is just finished.-   (S619) If the discontinuous number for cancellation t is equal to    the threshold value T, it determines that broadcast wave is not    received normally. Then, “off service” signal is output to the    payload formation unit 103, and is transmitted to receiving    apparatus 2.

According to the retransmission apparatus, the system and the method ofthe present invention for retransmitting the broadcast packets, which isexplicitly able to inform a plurality of receiving apparatus of thatbroadcast wave itself cannot be received, without wasting communicationresources in an IP network.

Many widely different embodiments of the present invention may beconstructed without departing from the spirit and scope of the presentinvention. It should be understood that the present invention is notlimited to the specific embodiments described in the specification,except as defined in the appended claims.

1. A retransmission apparatus for retransmitting TS packets based onreceived broadcast wave to a plurality of receiving apparatus through anetwork, wherein said retransmitting apparatus comprising: TS packetdetermination means for determining whether a continuity of circulationcounter values in the TS packets keeps in length equal to or more largerthan a first predetermined threshold value N, and for retransmittingthese TS packets when the determination is true, or for canceling theseTS packets when the determination is false.
 2. The retransmissionapparatus as claimed in claim 1, wherein, said TS packet determinationmeans determines whether a discontinuity of circulation counter valuesin the TS packets keeps in length equal to or more larger than a secondpredetermined threshold value T without retransmitting these TS packets,and sends an off service signal to a plurality of receiving apparatuswhen the determination is true.
 3. The retransmission apparatus asclaimed in claim 1, wherein, for the case that the circulation countervalue of the current TS packet is continuous to the circulation countervalue of the adjacent TS packet, said TS packet determination meansreserves the current TS packet, sets the continuous number of normallyreceived packets n=n+1, sets the discontinuous number for cancellationof t=t+1, and transmits all TS packets reserved in the buffer, then setst=0, when the continuous number of normally received packets n isdetermined to be equal to or larger than the first predetermined valueN.
 4. The retransmission apparatus as claimed in claim 3, wherein, forthe case that the circulation counter value of current TS packet isdiscontinuous to the circulation counter value of the adjacent TSpacket, said TS packet determination means cancels all TS packetsreserved, reserves current TS packet into a buffer, sets the continuousnumber of normally received packets n=0, sets the discontinuous numberfor cancellation t=t+1, and sends off service signal, when thediscontinuous number for cancellation t is determined to be equal to asecond predetermined value T.
 5. The retransmission apparatus as claimedin claim 1, wherein, TS packet is based on the standard of ARIB STD-B31,and a circulation counter value is a value of TSP_counter.
 6. Theretransmission apparatus as claimed in claim 1, wherein, the apparatusfurther has: payload formation means for forming a payload out of TSpackets from said TS packet determination means, RTP processing meansfor generating an RTP packet from the payload, IP multicast sendingmeans for forming RTP packet into IP packet sent to a plurality ofreceiving apparatus by multicast communication.
 7. A retransmissionsystem comprising: antenna for receiving digital broadcast wave from abroadcasting station, a plurality of tuners connected to the antenna fortuning every channel, and a plurality of retransmission apparatusclaimed in claim 1 connected to the tuner, wherein the retransmissionsystem sends IP packets including TS packets to a plurality of receivingapparatus through an IP network.
 8. A retransmission method on anapparatus that receives TS packets based on a broadcast wave, forretransmitting TS packets to a plurality of receiving apparatus througha network, wherein said method comprising the steps of: taking acirculation counter value in a TS packet at every TS packet input,determining whether a continuity of circulation counter values keepsequal to or larger than a first predetermined threshold value N, andretransmitting these TS packet when the determination is true, orcanceling these TS packets when the determination is false.
 9. Aretransmission method for making a computer to function as aretransmission apparatus for retransmitting TS packets based on receivedbroadcast wave to a plurality of receiving apparatus through a network,wherein said retransmission method comprising the steps of: taking acirculation counter value in a TS packet at every TS packet inputting,determining whether a continuity of circulation counter values keepsequal to or larger than a first predetermined threshold value N, andretransmitting these TS packet when the determination is true, orcanceling these TS packets when the determination is false.